1. Field of the Invention
This invention relates to devices used to measure nerve conduction in peripheral nerves and more particularly, to such devices that measure the conduction time and amplitude of a test signal applied to a nerve.
2. Description of the Related Art
It is common practice in medicine to measure the electrical conduction on a peripheral nerve. For example, when diagnosing carpel tunnel syndrome it is common for a physician to measure the electrical conduction in the median nerve as it extends from the forearm, through the wrist and into the hand. During the test procedure, the physician measures the length of time and the amplitude of a test signal applied to the nerve having a known length. To perform the test, recording sensors are attached to the patient's forearm and a nerve stimulator is positioned over the nerve.
When testing for carpel tunnel syndrome, the recording sensors and the nerve stimulator's cathode probe must be spaced apart at selected distances (8 cm, 10 cm, and 14 cm) on the hand and forearm. Heretofore, physicians have used a ruler or measuring tape and an ink marker to first mark the specific locations of the recording electrodes and the nerve stimulator on the patient's skin before the test is performed. Often, several tests are performed on the same hand and forearm during the visit, which requires manually marking the skin reference points. The act of measuring and marking several sets of reference points on the forearm and hand is very time consuming. Also, because the sets of reference points are relatively close, a wrong set of reference points may be used during the test that produces inaccurate readings.